Another ultra-wealthy investor has joined the partnership seeking to buy the Sacramento Kings and keep the team here, while city officials took the first legal steps toward making the team's proposed new arena a reality.

Chris Kelly, a former Facebook executive who ran for state attorney general in 2010, has joined the investor group.

Kelly joins Silicon Valley executive Vivek Ranadive; members of San Diego's Jacobs family; Sacramento developer Mark Friedman; and East Bay health club financier Mark Mastrov. A source familiar with the situation said the group has been speaking with Kelly for more than two months and his involvement in the bid was mentioned during the contingent's presentation to the NBA last week in New York.

The group is seeking to buy the Kings and block the franchise's proposed move to Seattle. While the Maloof family, which currently owns the franchise, has set a 5 p.m. deadline today to receive a written, binding offer from the Sacramento contingent, it is unclear if that formal bid will be submitted by that time - or whether the NBA is also requiring a written offer today.

"I am very excited to be a part of this once in a lifetime opportunity," Kelly said on Twitter.

The NBA Board of Governors is scheduled to vote next week on which bid to accept, although that decision could get postponed.

The Sacramento-based investors are in constant communication and are in the process of finalizing their bid, a source said. Mayor Kevin Johnson says Sacramento's group has told the Maloofs its offer is "better than competitive" with Seattle's.

The mayor, taking to Twitter, called Kelly's participation "exciting news."

"When we started this project I never imagined so many important leaders from across (California would) become a part of it," Johnson tweeted. "We have Californians who've helped create Tibco (Ranadive), 24-hour Fitness (Mastrov), Qualcomm (the Jacobses) and now Facebook all working for the future of Sacramento."